a punctuation mark (/) used e.g. esp to denote ‘per’ (e.g. in metres/second), ‘or’ (e.g. in and/or), to separate alternatives, the terms of a fraction (e.g. in 19/20), or the components of a date (e.g. in 19/10/99)
a curve, usu on a graph showing the relationship between temperature and composition for a mixture, below which only the solid phase can exist
an ancient Roman gold coin introduced by Constantine and used until the fall of the Byzantine Empire
[Middle English via late Latin from Latin solidus solid1; (sense 1) late Latin solidus shilling, from its former use as a symbol for shillings]